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Fuel Tank Protection?

Piper J3

Well Known Member
I recently had to remove my fuel tank to fix a small leak in the top cover seam. I used Van’s 2-part Fuel Tank Sealant and it worked a wonder. When I removed the tank I noticed debris under the tank that was trapped between the baggage floor and the bottom of the tank. The airplane has 350TT and lots of “stuff” has been hauled in the baggage compartment.

My concern is if something should accidentally roll under the tank it could cause chaffing and maybe wear a hole in the bottom of the tank. The tank is suspended about 1/8” above the baggage floor and may even be less clearance when weighted with fuel. I’m also concerned with the flathead screws holding the floor under the tank. If these screws loosen they can easily rise up and chafe against the bottom of the tank.

So I’ve been thinking about this problem and decided to slide a piece of flat cork sheet under the tank to prevent unwanted items from finding their way under the void. The cork sheet will also prevent a floor screw from backing out and touching the bottom of the tank. I found 1/8” x 12” x 20” cork sheet at the local craft store. Cork also comes in 1/16” thickness.

For what it’s worth…
 
Not sure I would put cork under it. Cork will retain moisture and can contribute to corrosion.
 
Actually, I think I?ll be OK. Cork is waterproof and naturally mold resistant as well. Apparently cork contains something called suberin, a natural fatty substance that makes cork waterproof. I guess this is what makes cork good for plugging the end of a wine bottle, although I wouldn't know anything about that...
 
The cork itself may be waterproof, but cork sheets are porous; they'll soak up liquids and hold them like a sponge via surface tension. The cork used to seal wine bottles is much more dense, thus no leak.
 
Hello Jim

I purchased a Fuel tank pad from Flyboys Accessories (their add is on this site) and put it under my tank. Now as you know the clearance under the tank gets larger from the back baggage wall to the center structure. So I positioned this pad where it would make good contact with bottom of the tank, but not push the back up to much.

Where those flush screws are, and any other spots where any contact between floor and tank appear in the bottom back, I use some heavy anti chaff tape. This tape is one inch wide and has a peel off backing to expose the sticky side. As I recall after the first year I removed the tank and noted a few spots in the back area that left coresponding scuff on the tank bottom. This was four years ago now and no issues with the tape barrier.

Also the Fuel tank pad has a peel off side to be able stick it down. Not being sure if I would continue to use it, and where I would place it, I never stuck it down. I would say it ended up between the baffle and back of the tank.
 
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